1. Field of the Invention
The present invention relates to a semiconductor device and a method for manufacturing the same, and more particularly to a semiconductor device and a method for manufacturing the same which are applied to a ferroelectric storage device (FeRAM: Ferroelectric Random Access Memory), or the like.
2. Description of the Related Art
Attention has recently been paid, as one of nonvolatile semiconductor memory devices, to a ferroelectric storage device (FeRAM) using a ferroelectric capacitor. In view of an area penalty, a Capacitor On Plug (COP) structure is adopted. In the COP structure, the ferroelectric capacitor is disposed above a memory cell transistor, and a capacitor electrode of the ferroelectric capacitor is connected with a source region or a drain region of the memory cell transistor through a contact plug (see, e.g., JP-2005-174977-A and US-2005-0121709-A). Also, from a viewpoint of an increase in operation margin, a Chain-FeRAM™ is proposed. In the Chain-FeRAM™, a unit cell includes the memory cell transistor MT and the ferroelectric capacitor CFE connected electrically in parallel with each other, and plurality of the unit cells are connected in series.
However, in the COP structure, the depth from a metal interconnecting wire that is disposed above the ferroelectric capacitor to a semiconductor substrate becomes larger. It results in a difficulty in forming a contact opening and embedding the contact opening with metal, thereby deteriorating a production yield of a contact plug (see; for example, JP-2004-335918-A and U.S. Pat. No. 6,897,502).